The purpose of this research was to study sole arch index and its relationship to non – contact ankle sprain in athletes. For this purpose, 120 male athletes who have held championship of wrestling and karate for more than one year (mean of 20.68±2.63 age, 73.97±6.61 cm height and 70.80±10.30 kg weight) participated in this study. The data were collected by a questionnaire and Chippaux – Smirak Index (CSI) was used to evaluate sole arch index. Data were analyzed by descriptive statistics, Mann – Whitney test and Spearman correlation coefficient (P? 0.05). The rate of sprain in wrestlers was 36.6% while in karate players was 46.66%. The left foot (the dominant foot) in karate players with 60.71% had the highest incidence of sprain while the right foot (the dominant foot) in wrestlers with 77.27%. The severity of the non – contact sprain of the ankle was not the same in karate and wrestling and the results showed that the severity was higher in wrestling than in karate (P=0.001). The results indicated a significant difference in the sole arch between injured and healthy karate players: healthy athletes had a decreased sole arch of their right leg when compared to injured athletes (P=0.236). The results of this study showed that the severity of injury was different in sports depending on the type and nature of that sport, and that, by knowing the features of different sports, effective steps could be taken to prevent and reduce the rate of ankle sprain in athletes. In addition, paying attention to the natural structure of the foot is very important as any disorder in the structure of the foot leads to an inappropriate distribution of pressure on the foot which in turn causes ankle sprain in these athletes. Therefore emphasizing the features of sole arch, one can, to some extent, relieve these athletes of the problems of the non – contact ankle sprain.